Allowing IMG tags for Forum Participants

Hi, I apologize in advance because it seems like this would be a commonly asked question (and one with a straight-forward solution), but I just can’t seem to find an answer.

How do I grant forum participants permission to use IMG tags? I don’t need to allow users to upload images inline, I just want to give them the same ability as the Administrator has to embed images using the IMG tags.

Unless I’m a total idiot, there doesn’t seem to be a built in UI to adjust this user permissions. Is there a simple line of code I can add in somewhere, or does this require a plugin? I prefer a non-plugin solution if possible.

I am using the User Role Plugin, but not sure how I could use this to enable the permission I’m looking for.